Internal combustion engine cooling device and internal combustion engine cooling method

Abstract

The present invention provides a cooling device for an internal combustion engine and a cooling method for an internal combustion engine. The cooling device includes: a first passage connected to the internal combustion engine and through which cooling water circulates; a second passage connected to the internal combustion engine and through which the cooling water circulates; a heat exchanger disposed in the first passage and configured to perform heat exchange with the cooling water; a first pump disposed in the first passage; a second pump disposed in the second passage; and an electronic control unit that controls the first pump and the second pump. When the temperature of the cooling water is above a predetermined temperature, the electronic control unit performs the following first control: the first pump is driven so as to increase the flow rate of the cooling water in the first passage compared to a case where the temperature of the cooling water is below the predetermined temperature, and the second pump is stopped.

Description

Technical Field

[0001] The present invention relates to a cooling device and a cooling method for an internal combustion engine. Background Art

[0002] A cooling device is installed in a vehicle to cool an internal combustion engine. The cooling device includes a cooling water channel for circulating cooling water, a pump, and a heat exchanger (radiator). A device that connects two cooling water channels to an internal combustion engine and includes a pump in each channel is disclosed (for example, Japanese Patent Application Laid-Open No. 2011-169237). Summary of the Invention

[0003] There is a risk that the cooling water flowing in the two cooling water passages will interfere with each other, increasing the pressure loss (pressure drop) on the pump. The increase in pressure drop will hinder the flow of cooling water and reduce cooling performance.

[0004] The present invention provides a cooling device and a cooling method for an internal combustion engine capable of improving cooling performance.

[0005] The first embodiment of the present invention relates to a cooling device for an internal combustion engine comprising a first passage, a second passage, a heat exchanger, a first pump, a second pump, and an electronic control unit. The first passage is connected to the internal combustion engine and configured to circulate cooling water. The second passage is connected to the internal combustion engine and configured to circulate the cooling water. The heat exchanger is provided in the first passage and configured to perform heat exchange with the cooling water. The first pump is provided in the first passage. The second pump is provided in the second passage. The electronic control unit is configured to control the first pump and the second pump. Furthermore, the electronic control unit is configured to perform the following first control when the temperature of the cooling water is above a predetermined temperature: the first pump is driven so as to increase the flow rate of the cooling water in the first passage compared to a case where the temperature of the cooling water is lower than the predetermined temperature, and the second pump is stopped.

[0006] In the cooling device according to the first aspect, the electronic control unit may be configured to maximize the rotation speed of the first pump during the first control.

[0007] In the cooling device of the above-mentioned first scheme, the electronic control unit may be configured to perform the following second control when the internal combustion engine performs a transition operation from a low load to a high load: the first pump is driven in a manner that increases the flow rate of the cooling water in the first passage compared to a case where the transition operation is not performed, and the second pump is driven in a manner that increases the flow rate of the cooling water in the second passage compared to a case where the transition operation is not performed.

[0008] In the cooling device having the above-described configuration, the electronic control unit may be configured to perform the second control when an increase in the intake air amount of the internal combustion engine is equal to or greater than a predetermined amount.

[0009] In the cooling device having the above configuration, the electronic control unit may be configured to perform the second control when an amount of increase in an accelerator opening of the internal combustion engine is equal to or greater than a predetermined amount.

[0010] In the cooling device having the above-described configuration, the electronic control unit may be configured to stop the second control when the second control continues for a predetermined time or longer.

[0011] In the cooling device of the first embodiment, the first passage and the second passage may share a portion, the first pump may be provided in the first passage at a position upstream of the shared passage, and the second pump may be provided in the second passage at a position upstream of the shared passage.

[0012] The second embodiment of the present invention relates to a cooling method for an internal combustion engine. Here, a first passage configured to circulate cooling water is connected to the internal combustion engine. A second passage configured to circulate the cooling water is connected to the internal combustion engine. A heat exchanger configured to perform heat exchange on the cooling water is provided in the first passage. A first pump is provided in the first passage. Furthermore, a second pump is provided in the second passage. In the cooling method, (i) when the temperature of the cooling water is higher than a predetermined temperature, the first pump is driven so as to increase the flow rate of the cooling water in the first passage compared to a case where the temperature of the cooling water is lower than the predetermined temperature, and (ii) when the temperature of the cooling water is higher than the predetermined temperature, the second pump is stopped.

[0013] According to the cooling device for an internal combustion engine of the first embodiment and the cooling method for an internal combustion engine of the second embodiment, the flow rate of cooling water flowing into the internal combustion engine is increased and the cooling water is introduced into the internal combustion engine at a high flow rate, thereby improving the cooling performance of the internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements.

[0015] Figure 1 This is a schematic diagram of a cooling device for an internal combustion engine as an example of the present invention.

[0016] Figure 2 This is an example Figure 1Flowchart of the processing performed by the electronic control unit (ECU) shown.

[0017] Figure 3A This is a flowchart illustrating the control of the cooling device at a high water temperature.

[0018] Figure 3B This is a flowchart illustrating the control during transient operation of the cooling device. DETAILED DESCRIPTION

[0019] Hereinafter, the cooling device for an internal combustion engine according to the present embodiment will be described with reference to the drawings. Figure 1 1 is a schematic diagram illustrating a cooling device 100. The cooling device 100 is mounted on a vehicle and cools an internal combustion engine 10. The internal combustion engine 10 is, for example, a gasoline engine and includes a cylinder block 12 and a cylinder head 14.

[0020] The cylinder block 12 and cylinder head 14 are formed of metal such as aluminum alloy. The cylinder head 14 is mounted on the cylinder block 12. A combustion chamber is formed in the cylinder head 14. The internal combustion engine 10 includes a water jacket 16. The water jacket 16 extends over the cylinder block 12 and cylinder head 14, surrounds the combustion chamber, and stores cooling water inside.

[0021] An intake passage 20 and an exhaust passage 22 are connected to the cylinder head 14 of the internal combustion engine 10. An air filter 24, an air flow meter 25, and a throttle valve 26 are provided in the intake passage 20, sequentially from the upstream side to the downstream side. The air filter 24 purifies the air. The air flow meter 25 detects the air flow rate. The throttle valve 26 regulates the air flow rate. Increasing the opening of the throttle valve 26 increases the air flow rate. Decreasing the opening decreases the air flow rate. The exhaust passage 22 is provided with components (not shown), such as a catalyst, that purify the exhaust gas.

[0022] Air is introduced into the internal combustion engine 10 through an intake passage 20. Fuel such as gasoline is supplied from a fuel injection valve (not shown). In the combustion chamber of the internal combustion engine 10, a mixture of air and fuel combusts, generating power. Exhaust gas generated during combustion is discharged through an exhaust passage 22. A portion of the exhaust gas is circulated back to the intake passage 20 via an EGR (Exhaust Gas Recirculation) device (not shown).

[0023] Cooling device 100 includes multiple cooling water passages. Cooling water passages 30, 32, 34, and 35 are connected to water jacket 16. Cooling water passages 31, 33, and 36 branch from cooling water passage 30. Cooling water passages 31, 33, and 35 merge to form cooling water passage 37. Cooling water passage 36 and cooling water passage 37 merge to form cooling water passage 32. Cooling water passage 34 branches from the middle of cooling water passage 32.

[0024] Cooling water passages 30, 36, and 32 form a first passage 40 through which cooling water circulates. Cooling water passages 30, 31, 33, 37, and 32 form a second passage 42 through which cooling water circulates. Cooling water is supplied to the internal combustion engine 10 and accumulated in the water jacket 16, thereby cooling the internal combustion engine 10. The cooling water is discharged from the internal combustion engine 10, undergoes heat exchange with components described later, and is then supplied to the internal combustion engine 10 again.

[0025] The connection point of the internal combustion engine 10 with the cooling water passage 30 is the outlet of the cooling water. A temperature sensor 44 is provided at the connection point of the cooling water passage 30 with the internal combustion engine 10. Temperature sensor 44 detects the temperature of the cooling water at the outlet of the internal combustion engine 10. The connection point of the internal combustion engine 10 with the cooling water passage 32 is the inlet of the cooling water. A temperature sensor 46 is provided upstream of the connection point with the cooling water passage 34 in the cooling water passage 32. Temperature sensor 46 detects the temperature of the cooling water at the inlet of the internal combustion engine 10.

[0026] An automatic transmission fluid heat exchanger (ATF / W) 48 is provided in cooling water passage 31. A heater 50 is provided in cooling water passage 33. An EGR cooler 51 is provided in cooling water passage 35. An oil cooler 52 is provided in cooling water passage 34. Cooling water is supplied to the above-mentioned components for heat exchange. A pump 57 (second pump) is provided in cooling water passage 37.

[0027] A radiator 54 (heat exchanger) and a pump 56 (first pump) are provided in the cooling water passage 36. The radiator 54 is a heat exchanger formed of a metal such as an aluminum alloy. Cooling water is introduced into the interior of the radiator 54 and cooled therein. The cooling water downstream of the radiator 54 is lower in temperature than the cooling water upstream and the cooling water in the second passage 42. A fan 55 is located near the radiator 54. The fan 55 blows air toward the radiator 54, cooling it. The pump 56 is located downstream of the radiator 54.

[0028] The electronic control unit (ECU) 60 (also referred to as a control unit) includes a computing device such as a CPU (Central Processing Unit), and storage devices such as a flash memory, a ROM (Read Only Memory), and a RAM (Random Access Memory), and performs various controls by executing programs stored in the storage devices.

[0029] The ECU 60 obtains the air flow rate from the air flow meter 25 , the water temperature at the outlet from the temperature sensor 44 , and the water temperature at the inlet from the temperature sensor 46 . The ECU 60 controls the opening of the throttle valve 26 and the fan 55 .

[0030] ECU 60 controls pumps 56 and 57. When the rotation speed of pump 56 increases, the flow rate of cooling water in first passage 40 increases. When the rotation speed of pump 56 decreases, the flow rate of cooling water in first passage 40 decreases. When pump 56 stops, the flow of cooling water in first passage 40 stops. When the rotation speed of pump 57 increases, the flow rate of cooling water in second passage 42 increases. When the rotation speed of pump 57 decreases, the flow rate of cooling water in second passage 42 decreases. When pump 57 stops, the flow of cooling water in second passage 42 stops.

[0031] The cooling device 100 includes a first passage 40 and a second passage 42 through which cooling water circulates. By controlling the flow of cooling water in these two passages according to the operating state of the internal combustion engine 10, the cooling performance of the internal combustion engine 10 can be improved.

[0032] Figure 2 This is a flowchart illustrating the processing performed by the ECU 60. The ECU 60 obtains the water temperature T at the outlet of the internal combustion engine 10 from the temperature sensor 44 and determines whether the water temperature T is above the predetermined temperature Tth (step S10). In the case of a positive determination (yes), the ECU 60 performs high water temperature control (also referred to as the first control) (step S12). The high water temperature control will be described later. After step S12, Figure 2 The processing is completed.

[0033] In the case of a negative determination (No) in step S10, ECU60 determines whether the duration L of the transition operation control described later is less than a predetermined time Lth (step S14). The time Lth is set to a range of 5 seconds to 20 seconds, for example. In the case of a positive determination, ECU60 continues the transition operation control (step S16). The transition operation control will be described later. After step S16, Figure 2 The processing is completed.

[0034] If a negative determination is made in step S14, the ECU 60 obtains the intake air volume from the air flow meter 25 and determines whether the increase in intake air volume ΔA within a predetermined time (e.g., within a few seconds) is greater than a predetermined value Ath (step S17). If a positive determination is made, the ECU 60 resets the counter for measuring the duration L (step S18) and performs transitional operation control (also referred to as second control) (step S16). If a negative determination is made, the ECU 60 performs temperature control (step S19). For example, the ECU 60 activates the two pumps 56 and 57 to adjust the water volume in the first passage 40 and the water volume in the second passage 42 to perform temperature control.

[0035] Figure 3A This is a flowchart illustrating the control at high water temperature. ECU60 stops pump 57 (step S20). The water flow in the second passage 42 stops. ECU60 drives pump 56 at the maximum speed (step S22). After step S22, Figure 3A The processing is completed.

[0036] By driving pump 56 at maximum speed, the flow rate of cooling water in first passage 40 increases, and the amount of cooling water supplied to radiator 54 increases. Since pump 57 is stopped, interference between the cooling water flowing in cooling water passage 36 and the cooling water in cooling water passage 37 is suppressed. Since the pressure loss of pump 56 is suppressed, the flow rate of cooling water in first passage 40 is effectively increased. A portion of the cooling water also flows from cooling water passage 36 to cooling water passage 37, and is supplied to radiator 54 through cooling water passage 36. By increasing the amount of cooling water supplied to radiator 54, more cooling water is cooled by radiator 54. The cooled cooling water is introduced into internal combustion engine 10. By controlling the water temperature at high temperatures, internal combustion engine 10 can be effectively cooled.

[0037] Figure 3B This is a flowchart illustrating the control during transition operation. Transition operation means the operation when the internal combustion engine 10 transfers from low load to high load. ECU60 drives the pump 56 at the maximum speed (step S24) and drives the pump 57 at the maximum speed (step S26). ECU60 starts the counter and measures the duration L from the start of the transition operation control (step S28). Figure 3B The processing is completed.

[0038] By driving pumps 56 and 57 at their maximum rotational speed, the flow rate of the cooling water in first passage 40 and second passage 42 increases, maximizing the flow rate of the cooling water flowing into internal combustion engine 10. This increased flow rate improves cooling performance, enhancing the responsiveness of internal combustion engine 10 and enabling rapid cooling of internal combustion engine 10, thereby suppressing temperature increases.

[0039] According to this embodiment, when the temperature T of the cooling water is Tth or higher, as Figure 3A shown, the ECU 60 stops the pump 57 to stop the flow of the cooling water in the second passage 42. The ECU 60 drives the pump 56 so as to increase the flow rate of the cooling water in the first passage 40 compared to the state other than the high temperature case (when T < Tth), and circulates the cooling water to the first passage 40. Since the water flow in the second passage 42 is stopped, the water flow in the first passage 40 is not easily obstructed. The backflow of water from the first passage 40 to the second passage 42 (cooling water passage 37) is also allowed. The pressure loss of the pump 56 is suppressed, and the flow of the cooling water in the first passage 40 is easily increased. The cooling performance is improved by introducing the cooling water into the radiator 54 and cooling the cooling water. The internal combustion engine 10 is cooled by introducing the cooling water cooled by the radiator 54 into the internal combustion engine 10. The internal combustion engine 10 in a high temperature state can be effectively cooled, and overheating and the like can be suppressed.

[0040] In the high water temperature control, the ECU 60 preferably increases the output of the pump 56 to 90% or more, 95% or more, etc., and particularly preferably drives the pump 56 at the maximum rotational speed (output 100%) ( Figure 3A step S22). Since the flow rate of the cooling water in the first passage 40 increases, the temperature drop of the cooling water by the radiator 54 and the cooling of the internal combustion engine 10 can be promoted.

[0041] The first passage 40 and the second passage 42 share the cooling water passage 32. The water flows in the first passage 40 and the second passage 42 converge at the cooling water passage 32. If the two water flows collide, the pressure loss of the pump increases. By stopping the pump 57, the water flow in the second passage 42 is stopped. The pressure loss of the pump 56 caused by the interference of the water flows is suppressed, and the water flow in the first passage 40 can be increased. Since more cooling water flows to the radiator 54 and is cooled, the cooling performance is improved.

[0042] If the water temperature T is lower than Tth, the risk of overheating is low. However, during the transition operation from low load operation to high load operation, the temperature of the internal combustion engine 10 tends to rise. When the increase amount ΔA of the intake air amount is a predetermined value Ath or more, the internal combustion engine 10 is in a transition operation state. At this time, the ECU 60 drives the pumps 56 and 57 so as to increase the flow rates of the cooling water in the first passage 40 and the second passage 42 ( Figure 3B)。The cooling water flowing into the internal combustion engine 10 from the first passage 40 and the second passage 42 increases. By introducing the cooling water into the internal combustion engine 10 at a high flow rate, the cooling performance is improved. By rapidly cooling the internal combustion engine 10, knocking during transitional operation can be suppressed. Since measures against knocking such as delaying ignition timing do not need to be performed, deterioration of fuel economy, decrease in torque, etc. are suppressed. The ECU 60 can also drive the pumps 56 and 57 at the maximum rotational speed. By making the flow rate of the cooling water to the internal combustion engine 10 maximum, effective cooling can be achieved.

[0043] As described above, by performing Figure 3B the transitional operation control, the responsiveness of the cooling device 100 is improved, and the internal combustion engine 10 is rapidly cooled. The temperature of the cooling water after cooling for the internal combustion engine 10 rises. The temperature rise of the cooling water is detected by the temperature sensor 44, and at high temperatures, the ECU 60 performs Figure 3A the high water temperature control. Cooling of the cooling water by the radiator 54 is prioritized. The internal combustion engine 10 can be cooled using the cooled cooling water, and the temperature rise can be suppressed. According to the present embodiment, improvement in responsiveness during transitional operation and improvement in cooling performance at high temperatures can be achieved simultaneously.

[0044] If the duration L of the transitional operation control is Lth or more, the ECU 60 stops the transitional operation control. After that, at high temperatures (T≥Tth), the ECU 60 performs Figure 3A the high water temperature control. Also, if it is not a high temperature (T<Tth), the ECU 60 performs temperature control ( Figure 2 step S19). The ECU 60 drives both the pumps 56 and 57, controls their rotational speeds, and adjusts the flow rate of the cooling water in the first passage 40 and the flow rate of the cooling water in the second passage. The temperature of the cooling water is maintained within an appropriate range. For example, if the temperature of the cooling water rises above a predetermined temperature, the rotational speed of the pump 56 is increased, and the flow rate of the cooling water in the first passage 40 is increased. The cooling water cooled by the radiator 54 increases. If the temperature of the cooling water drops below a predetermined temperature, the rotational speed of the pump 56 is decreased, and the cooling water cooled by the radiator 54 is reduced.

[0045] As Figure 2 shown, it is determined whether to perform the high water temperature control based on the temperature of the cooling water at the outlet portion of the internal combustion engine 10 detected by the temperature sensor 44. Not only the water temperature detected by the temperature sensor 44, but also the cooling water temperature at the inlet portion detected by the temperature sensor 46 can be used for the determination. In addition to the increase amount of the intake air amount, for example, it can also be determined as transitional operation when the increase amount of the depression amount of an accelerator pedal (accelerator opening) not shown is a predetermined amount or more.

[0046] As mentioned above, although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

Claims

1. A cooling device for an internal combustion engine, characterized in that: have: The first passage is connected to the internal combustion engine and is configured to circulate cooling water; a second passage connected to the internal combustion engine and configured to circulate the cooling water; a heat exchanger disposed in the first passage and configured to perform heat exchange with the cooling water; a first pump disposed in the first passage; a second pump disposed in the second passage; and an electronic control unit configured to control the first pump and the second pump, The electronic control unit is configured to perform a first control when the temperature of the cooling water is above a predetermined temperature. In the first control, the first pump is driven in a manner that increases the flow rate of the cooling water in the first passage compared to a case where the temperature of the cooling water is lower than the predetermined temperature, and the second pump is stopped and the circulation of the cooling water in the second passage is stopped.

2. The cooling device for an internal combustion engine according to claim 1, wherein: The electronic control unit is configured to maximize the rotation speed of the first pump during the first control.

3. The cooling device for an internal combustion engine according to claim 1 or 2, characterized in that: The electronic control unit is configured to perform a second control when the internal combustion engine performs a transition operation from a low load to a high load. In the second control, the first pump is driven so as to increase the flow rate of the cooling water in the first passage, and the second pump is driven so as to increase the flow rate of the cooling water in the second passage, compared to a case where the transition operation is not performed.

4. The cooling device for an internal combustion engine according to claim 3, characterized in that The electronic control unit is configured to perform the second control when an increase in the intake air amount of the internal combustion engine is equal to or greater than a predetermined amount.

5. The cooling device for an internal combustion engine according to claim 3, wherein: The electronic control unit is configured to perform the second control when an increase in an accelerator opening of the internal combustion engine is equal to or greater than a predetermined amount.

6. The cooling device for an internal combustion engine according to claim 3, wherein: The electronic control unit is configured to stop the second control when the second control continues for a predetermined time or longer.

7. The cooling device for an internal combustion engine according to claim 1 or 2, characterized in that: a passage having a portion in common with the first passage and the second passage, The first pump is provided on the upstream side of the common passage in the first passage, and The second pump is provided in the second passage on the upstream side of the common passage.

8. A method for cooling an internal combustion engine, A first passage configured to circulate cooling water is connected to the internal combustion engine. The second passage for circulating the cooling water is connected to the internal combustion engine. A heat exchanger configured to perform heat exchange with the cooling water is provided in the first passage. The first pump is provided in the first passage, and The second pump is provided in the second passage. The cooling method is characterized by comprising: When the temperature of the cooling water is equal to or higher than a predetermined temperature, driving the first pump so as to increase the flow rate of the cooling water in the first passage compared to when the temperature of the cooling water is lower than the predetermined temperature; and When the temperature of the cooling water is equal to or higher than the predetermined temperature, the second pump is stopped and the circulation of the cooling water in the second passage is stopped.

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